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Transconductance (gm) is one important figure of merit for benchmarking organic electrochemical transistor (OECT) biosensors, which nevertheless experiences undesired fluctuation instead of keep constant during the target detection of varied concentrations. Light‐matter interplay is recently shown as a potential way to regulate the OECT characteristics, e.g. maximum gm at zero gate bias is achieved. In this work, the challenge of unstable gm is addressed by using a unique metal‐organic framework (MOF)‐derived hollow tube indium sulfide (m‐In2S3) as the photogate. Interestingly, the light irradiation on m‐In2S3 generate a straight transfer curve, leading to a stable gm that is desirable for biological application. Exemplifying by an aptasening, such a device is then tested for protein quantification with a stable sensitivity during the detection. This work features the feasibility of light‐matter interplay to achieve a stable gm in organic electronics. [ABSTRACT FROM AUTHOR]

Designing dynamic assemblies in living cells is crucial for creating organelle‐like structures, yet precisely controlling their morphological transitions in response to specific signals is a significant challenge. In this study, a DNA framework is combined with hybridization chain reaction (HCR) to achieve specific assembly of hyperbranched aggregates in cancer cells. HCR, distinguished for its signal amplification and linear extension capabilities, enables the morphological transition of precursors to be specifically triggered by trace amounts of endogenous microRNA‐21 (miR‐21). The spatial constraints of the framework and the diversity of hairpin orientations significantly accelerate the assembly kinetics of hyperbranched networks, and the resulting micrometer‐scale aggregates possess enhanced intracellular retention capabilities. Introducing Ce6 molecules as a proof of concept, the regulatory function of aggregates can be activated under light irradiation and remains effective over a long period. The probe we constructed demonstrates good stability and biocompatibility, offers easy functionalization, and works inside cells long‐term, making it an ideal candidate material for the construction of organelle‐like structures. [ABSTRACT FROM AUTHOR]

Full utilization of the excited species at both singlet states (1R*) and triplet states (3R*) is crucial to improving electrochemiluminescence (ECL) efficiency but is challenging for organic luminescent materials. Here, an aggregation‐induced delayed ECL (AIDECL) active organic dot (OD) containing a benzophenone acceptor and dimethylacridine donor is reported, which shows high ECL efficiency via reverse intersystem crossing (RISC) of non‐emissive 3R* to emissive 1R*, overcoming the spin‐forbidden radiative decay from 3R*. By introducing dual donor‐acceptor pairs into luminophores, it is found that nonradiative pathway could be further suppressed via enhanced intermolecular weak interactions, and multiple spin‐up conversion channels could be activated. As a consequence, the obtained OD enjoys a 6.8‐fold higher ECL efficiency relative to the control AIDECL‐active OD. Single‐crystal studies and theoretical calculations reveal that the enhanced AIDECL behaviors come from the acceleration of both radiative transition and RISC. This work represents a major step towards purely organic, high‐efficiency ECL dyes and a direction for the design of next‐generation ECL dyes at the molecular level. [ABSTRACT FROM AUTHOR]

We report here a tumor‐pretargted theranostic approach for multimodality imaging‐guided synergistic cancer PDT by cascade alkaline phosphatase (ALP)‐mediated in situ self‐assembly and bioorthogonal inverse electron demand Diels–Alder (IEDDA) reaction. Using the enzymatic catalysis of ALP that continuously catalyses the dephosphorylation and self‐assembly of trans‐cyclooctene (TCO)‐bearing P‐FFGd‐TCO, a high density of fluorescent and magnetic TCO‐containing nanoparticles (FMNPs‐TCO) can be synthesized and retained on the membrane of tumor cells. They can act as 'artificial antigens' amenable to concurrently capture lately administrated tetrazine (Tz)‐decorated PS (775NP‐Tz) and carbonic anhydrase (CA) inhibitor (SA‐Tz) via the fast IEDDA reaction. This two‐step pretargeting process can further induce FMNPs‐TCO regrowth into microparticles (FMNPs‐775/SA) directly on tumor cell membranes, which is analyzed by bio‐SEM and fluorescence imaging. Thus, efficient enrichment of both SA‐Tz and 775NP‐Tz in tumors can be achieved, allowing to alleviate hypoxia by continuously inhibiting CA activity and improving PDT of tumors. Findings show that subcutaneous HeLa tumors could be completely eradicated and no tumor recurred after irradiation with an 808 nm laser (0.33 W cm−2, 10 min). This pretargeted approach may be applied to enrich other therapeutic agents in tumors to improve targeted therapy. [ABSTRACT FROM AUTHOR]

The transport behavior of ions in the nanopores has an important impact on the performance of the electrochemical devices. Although the classical Transmission‐Line (TL) model has long been used to describe ion transport in pores, the boundary conditions for the applicability of the TL model remain controversial. Here, we investigated the transport kinetics of different ions, within nanochannels of different lengths, by using transient single‐particle imaging with temporal resolution up to microseconds. We found that the ion transport kinetics within short nanochannels may deviate significantly from the TL model. The reason is that the ion transport under nanoconfinement is composed of multi basic stages, and the kinetics differ much under different stage domination. With the shortening of nanochannels, the electrical double layer (EDL) formation would become the "rate‐determining step" and dominate the apparent ion kinetics. Our results imply that using the TL model directly and treating the in‐pore mobility as an unchanged parameter to estimate the ion transport kinetics in short nanopores/nanochannels may lead to orders of magnitude bias. These findings may advance the understanding of the nanoconfined ion transport and promote the related applications. [ABSTRACT FROM AUTHOR]

Construction of white‐light emitters is of great importance in practical applications but is challenging for metal nanoclusters. Herein, arginine (Arg)‐mediated copper nanoclusters (Cu NCs) assemblies with white‐light emission (WLE) are reported for the first time. The multidentate ligand, Arg, not only effectively tailors the high stability and locally‐excited emission (LES) of aqueous phase Cu NCs, but also bridges 1‐naphthalenol methylcarbamate (NMC) to generate a blue emitter via through‐space interactions (TSIs), resulting in a stable mixed light. Density functional theory calculation and mass spectrum further confirm that Arg can allow for the formation of strong hydrogen‐bonds with the ligand 2,4‐diaminotoluene of Cu NCs, and formation of TSIs‐based complexes with NMC. More importantly, pure white‐light emission (WLE) with Commission Internationale de L'Eclairagecoordination (0.30, 0.31) is observed by regulating the ratio between Arg and the interfacial ligand of NMC. The findings not only provide a new perspective for the construction of WLE emitters via interface modification chemistry but also open a window to gain insight into the mechanism of interface engineering. [ABSTRACT FROM AUTHOR]

Single‐cell epigenetics is envisioned to decipher manifold epigenetic phenomena and to contribute to our accurate knowledge about basic epigenetic mechanisms. Engineered nanopipette technology has gained momentum in single‐cell studies; however, solutions to epigenetic questions remain unachieved. This study addresses the challenge by exploring N6‐methyladenine (m6A)‐bearing deoxyribozyme (DNAzyme) confined within a nanopipette for profiling a representative m6A‐modifying enzyme, fat mass and obesity‐associated protein (FTO). Electroosmotic intracellular extraction of FTO could remove the m6A and cause DNAzyme cleavage, leading to the altered ionic current signal. Because the cleavage can release a DNA sequence, we simultaneously program it as an antisense strand against FTO‐mRNA, intracellular injection of which has been shown to induce early stage apoptosis. This nanotool thus features the dual functions of studying single‐cell epigenetics and programmable gene regulation. [ABSTRACT FROM AUTHOR]

Cuproptosis is a new form of programmed cell death and exhibits enormous potential in cancer treatment. However, reducing the undesirable Cu ion release in normal tissue and maximizing the copper‐induced therapeutic effect in cancer sites are two main challenges. In this study, we constructed a photothermally triggered nanoplatform (Au@MSN‐Cu/PEG/DSF) to realize on‐demand delivery for synergistic therapy. The released disulfiram (DSF) chelated with Cu2+ in situ to generate highly cytotoxic bis(diethyldithiocarbamate)copper (CuET), causing cell apoptosis, and the formed Cu+ species promoted toxic mitochondrial protein aggregation, leading to cell cuproptosis. Synergistic with photothermal therapy, Au@MSN‐Cu/PEG/DSF could effectively kill tumor cells and inhibit tumor growth (inhibition rate up to 80.1 %). These results provide a promising perspective for potential cancer treatment based on cuproptosis, and may also inspire the design of advanced nano‐therapeutic platforms. [ABSTRACT FROM AUTHOR]

Single‐cell protein therapeutics is expected to promote our in‐depth understanding of how a specific protein with a therapeutic dosage treats the cell without population averaging. However, it has not yet been tackled by current single‐cell nanotools. We address this challenge by the use of a double‐barrel nanopipette, in which one lumen was used for electroosmotic cytosolic protein delivery and the other was customized for ionic evaluation of the consequence. Upon injection of protein DJ‐1 through the delivery lumen, upregulation of the antioxidant protein could protect neural PC‐12 cells against oxidative stress from phorbol myristate acetate exposure, as deduced by targeting of the cytosolic hydrogen peroxide by the detecting lumen. The nanotool developed in this study for single‐cell protein therapeutics provides a perspective for future single‐cell therapeutics involving different therapeutic modalities, such as peptides, enzymes and nucleic acids. [ABSTRACT FROM AUTHOR]

Rational utilization of the rich light‐bio‐matter interplay taking place in single‐cell analysis represents a new technological direction in the field. The light‐fueled operation is expected to achieve advanced photoelectrochemical (PEC) single‐cell analysis with unknown possibilities. Here, a PEC nanoreactor capable of single‐cell sampling and near zero‐background Faradaic detection of intracellular microRNA (miR) is devised by the construction of a small reaction chamber accommodating the target‐triggered hybridization chain reaction for binding the metallointercalator of [Ru(bpy)2(dppz)]2+ as the signal reporter. Light stimulation of the dsDNA/metallointercalator adduct will induce the generation of photocurrents, underpinning a zero‐biased and near zero‐background PEC method toward Faradaic detection of non‐electrogenic miR at the single‐cell level. Using this nanotool, lower miR concentration in the near‐nucleus region than that in the main cytosol was revealed. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The review summaries our achievements in optical, electrochemical, as well as mass spectrometry analysis and imaging with high sensitivity, specificity, and spatiotemporal resolution. We promoted the plasmonic imaging system, and developed ultra‐sensitive plasmonic nanoprobes for the tracking of single molecules in single living cells, as well as plasmonic nanocatalysts for highly efficient energy conversion. In addition, we contributed a lot in electrogenerated chemiluminescence (ECL) analysis and imaging. Pioneering works including localized surface plasmon resonance (LSPR) enhanced ECL, ECL ratiometric detection, BPE based ECL system, multi‐color ECL sensing as well as super‐resolved ECL imaging have been initiated by our group. Furthermore, we also dedicated in nanopipette based electrochemical analysis in single living cells, as well as ESI‐MS analysis on short time scale. The research works of our group promoted the development of chemical measurement and analysis. What is the most favorite and original chemistry developed in your research group? LSPR enhanced ECL and Bipolar electrochemistry analysis, single particle based single cell analysis and super‐resolved imaging. What is the most important personality for scientific research? Strong curiosity, perseverance, strong hands‐on ability. How do you supervise your students? Encourage students to read more, think more, discuss more, and try more. How do you keep balance between research and family? Allocating time reasonably. Who influences you mostly in your life? My PhD director, Prof. Hong‐Yuan Chen. What are your hobbies? I used to like to play badminton, now I'm learning to play table tennis. [ABSTRACT FROM AUTHOR]

Since the concept of surface plasmon amplification by stimulated emission of radiation (SPASER) was proposed in 2003, great progresses have been made on two kinds of plasmonic nanolasers, namely SPASER device and SPASER nanoparticle. In comparison, SPASER nanoparticle, with ultra‐narrow emission line, small size, and good biocompatibility, is a kind of promising luminescent nanoprobe and has a bright application prospect in biomedical imaging and sensing. Hence, it is gradually becoming an attractive research hotspot in the world. However, as the research on SPASER nanoparticle is still in its infancy, there are still lots of problems to be solved before it is widely applied. In this paper, the latest research advances of SPASER nanoparticles and their biological applications are reviewed. Besides existing problems, challenges and opportunities of SPASER nanoparticles as next generation luminescent nanoprobes are discussed as well. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Inspired by the adaptation of cells to the surrounding environment, the combination of cell membrane and nanomaterials has gradually become a new type of biomimetic nanocomposite. The construction of endogenous membrane biomimetic nanocarriers (EMBNs) not only retains the structure of membrane surface protein, but also has the properties of nanoparticles (NPs), also provides the ability of natural interaction between nanomaterials and organisms, thus overcoming the severe challenges faced by traditional nanodelivery systems in clinical application. In this paper, the construction methods of EMBNs are reviewed, focusing on a simple method to prepare membrane proteins. Secondly, EMBNs were classified according a variety of cell membranes. Finally, the unique advantages of EMBNs in nanomedicine are introduced, including improving biocompatibility, homologous targeting ability, prolonging blood circulation time and immune escape ability. In nanomedicine, such as targeted delivery, phototherapy, immunotherapy and tumor imaging, multifaceted biological interfaces through membrane masking provide a new approach for the development of multifunctional NPs. [ABSTRACT FROM AUTHOR]

Photonic (bio)electronic circuits and devices have been an enduring goal in modern photonics and electronics. Organic photoelectrochemical transistor (OPECT) interfacing light with biological world creates a substantial opportunity to this end due to the immense light−bio−matter interplay. Through modulating the invisible ionic circuit of organic electrochemical transistor (OECT) with a bipolar electrode (BPE) accommodating different semiconductor combinations, the unique photonic electronics toward logic and sensor applications are realized. Six combinations of BPEs are produced by the representative n‐type CdS/TiO2 and p‐type BiOI/NiO semiconductors, and the corresponding photonic characteristics and operation rationale are systematically investigated and explained. Designation of opto‐logic circuits and feasibility as a sensory platform are subsequently demonstrated. This work not only represents new photonic bioelectronics but also provides a generic mechanism for the design and development of advanced opto‐logics and bio‐analytics. [ABSTRACT FROM AUTHOR]

Photoelectrochemical (PEC) cytosensors, a combination of the PEC process and the living‐cell assay, have emerged as a powerful tool in the analytical and biological science. This mini review provides a brief introduction of this arena and summaries the key steps about the development of PEC cytosensors with representative examples, followed by future prospects based on our own opinions. [ABSTRACT FROM AUTHOR]

We report a photodynamic therapy driven by electrochemiluminescence (ECL). The luminescence generated by Ru(bpy)32+ and co‐reactant tripropylamine (TPA) pair acts as both optical readout for ECL imaging, and light source for the excitation of photosensitizer to produce reactive oxygen species (ROS) in photodynamic therapy (PDT) system. The ECL‐driven PDT (ECL‐PDT) relies on the effective energy transfer from ECL emission to photosensitizer chlorin e6 (Ce6), which sensitizes the surrounding O2 into ROS. The dynamic process of gradual morphological changes, the variation of cell‐matrix adhesions, as well as the increase of cell membrane permeability in the process of ECL‐PDT were monitored under ECL microscopy (ECLM) with good spatiotemporal resolution. Combining real‐time imaging with ECL‐PDT, this new strategy provides not only new insights into dynamic cellular processes, but also promising potential of ECL in clinical applications. [ABSTRACT FROM AUTHOR]

Single‐nanoparticle electrochemistry offers electrochemical behaviors of individual entities beyond the ensemble system. An electric double layer (EDL) exists on any charged particle–liquid interface because of counter‐ion accumulation, while direct measuring of the interfacial ion migration remains a challenge. Herein, a plasmonic‐based transient microscopic method, with a temporal resolution of 1–2 μs, was demonstrated to directly track the ion migration dynamics on single charged nanoparticles. We found that the dynamics of EDL formation might deviate significantly from the prediction made by using the classical resistance–capacitance (RC) model under nanoscale and transient conditions. Under ultrafast charging, due to the limit migration rate of ions in the solution, the actual time scale of the EDL formation could be up to 5 times slower than the predicted value from the RC model. We then proposed a new theoretical model to describe the transient dynamics of EDL formation. These results may expand our current knowledge about nano‐electrochemistry and transient electrochemistry. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: SPASER nanoparticle (NP), with small size, ultranarrow spectral‐line and good biocompatibility, is a potential biomedical nanoprobe. However, owning to the striking light absorption capacity of Au‐resonator, huge energy could accumulate under strong pumping‐laser, which would lead to poor photo‐stability and unexpected photo‐damage to SPASER NP, and is harmful to its future practical application but hasn't been systematically studied in experiment. In this paper, our experimental and theoretical researches revealed that the photo‐stability of SPASER NP is largely determined by its structure parameters: smaller Au‐core diameter, thicker silica‐shell will contribute to better photo‐stability. And the possibility and extent of photo‐damage of SPASER NP depend on not only its intrinsic stability but also the external pumping‐laser. Notably, the strong pumping condition for two‐level SPASER system could lead to heating‐melting‐evaporation or even phase‐explosion of SPASER NP, resulting in obvious photo‐damage, while, the weak pumping condition for three‐level SPASER system is quite friendly. This study provides reliable bases for the structural‐properties optimization of SPASER NPs, which is of great significance for its future application as a novel luminescence probe. [ABSTRACT FROM AUTHOR]

Though great advances are achieved in the area of organic electrochemical transistor (OECT) biosensors, general issues of shared electrolyte by the channel and gate electrode remain unsolved. On the other hand, to date binding‐free OECT detection of cellular membrane proteins is not reported. On the basis of the advanced technique of organic photoelectrochemical transistor (OPECT), herein the H‐cell‐supported OPECT device that can easily circumvent the issues of abovementioned shared electrolyte and its application toward binding‐free detection of membrane alkaline phosphatase (ALP) of HeLa cells is demonstrated. In such a configuration, usage of a Nafion perfluorinated membrane equipped H‐cell can well retain the ionic circuit of the device but prevent the diffusion of various molecules and minimize the possible interference. In the detection, ALP catalytic chemistry enables the sensitization of the TiO2 nanotubes electrode, triggering enhanced de‐doping of the poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) and thus resulting in altered channel currents proportionate to the membrane ALP. This work not only provides a new perspective for binding‐free detection of membrane protein but also represents a general protocol for H‐cell‐supported OECT/OPECT biosensors with enhanced accuracy. [ABSTRACT FROM AUTHOR]

A label‐free and fast approach for positive electrochemiluminescence (ECL) imaging of single cells by bipolar nanoelectrode array is proposed. The reduction of oxygen at a platinized gold nanoelectrode array in a closed bipolar electrochemical system is coupled with an oxidative ECL process at the anodic side. For elevating the ECL imaging contrast of single cells, a driving voltage of −2.0 V is applied to in situ generate oxygen confined beneath cells that is subsequently used for ECL imaging at 1.1 V. High oxygen concentration in the confined space resulting from steric hindrance generates prominent oxygen reduction current at the cathodic side and higher ECL intensity at the anodic side, allowing positive ECL imaging of the cells adhesion region with excellent contrast. Cell morphology and adhesion strength can be successfully imaged with high image acquisition rate. This approach opens a new avenue for label‐free imaging of single cells. [ABSTRACT FROM AUTHOR]

With reduced background and high sensitivity, photoelectrochemistry (PEC) may be applied as an intracellular nanotool and open a new technological direction of single‐cell study. Nevertheless, the present palette of single‐cell tools lacks such a PEC‐oriented solution. Here a dual‐functional photocathodic single‐cell nanotool capable of direct electroosmotic intracellular drug delivery and evaluation of oxidative stress is devised by engineering a target‐specific organic molecule/NiO/Ni film at the tip of a nanopipette. Specifically, the organic molecule probe serves simultaneously as the biorecognition element and sensitizer to synergize with p‐type NiO. Upon intracellular delivery at picoliter level, the oxidative stress effect will cause structural change of the organic probe, switching its optical absorption and altering the cathodic response. This work has revealed the potential of PEC single‐cell nanotool and extended the boundary of current single‐cell electroanalysis. [ABSTRACT FROM AUTHOR]

A novel mass spectrometric method for probing the flash chemistry of electrogenerated reactive intermediates was developed based on rapid collision mixing of electrosprayed microdroplets by using a theta‐glass capillary. The two individual microchannels of the theta‐glass capillary are asymmetrically or symmetrically fabricated with a carbon bipolar electrode to produce intermediates in situ. Microdroplets containing the newly formed intermediates collide with those of the invoked reactants at sub‐10 microsecond level, making it a powerful tool for exploring their ultrafast initial transformations. As a proof‐of‐concept, we present the identification of the key radical cation intermediate in the oxidative dimerization of 8‐methyl‐1,2,3,4‐tetrahydroquinoline and also the first disclosure of previously hidden nitrenium ion involved reaction pathway in the C−H/N−H cross‐coupling between N,N′‐dimethylaniline and phenothiazine. [ABSTRACT FROM AUTHOR]

New tools for single‐cell interrogation enable deeper understanding of cellular heterogeneity and associated cellular behaviors and functions. Information of RNA expression in single cell could contribute to our knowledge of the genetic regulatory circuits and molecular mechanism of disease development. Although significant progresses have been made for intracellular RNA analysis, existing methods have a trade‐off between operational complexity and practical feasibility. We address this challenge by combining the ionic current rectification property of nanopipette reactor with duplex‐specific nuclease‐assisted hybridization chain reaction for signal amplification to realize a simple and practical intracellular nanosensor with minimal invasiveness, which enables single‐cell collection and electrochemical detection of intracellular RNA with cell‐context preservation. Systematic studies on differentiation of oncogenic miR‐10b expression levels in non‐malignant breast cells, metastatic breast cancer cells as well as non‐metastatic breast cancer cells were then realized by this nanotool accompanied by assessment of different drugs effects. This work has unveiled the ability of electrochemistry to probe intracellular RNA and opened new opportunities to study the gene expression and heterogeneous complexity under physiological conditions down to single‐cell level. [ABSTRACT FROM AUTHOR]

We report a new mass spectrometric method for detecting electrogenerated intermediates. This approach is based on simultaneous activation of electrospray ionization and redox reaction on a wireless bipolar ultramicroelectrode, which is fabricated in the tip of a quartz nanopipette. The hollow structure of the ultramicroelectrode permits rapid transferring the transient species from electrode–electrolyte interfaces into the gas phase for mass spectrometric identification on the time scale of microseconds. The long‐sought fleeting intermediates including TPrA.+, whose lifetime in solution is only 200 μs, and catecholamine o‐semiquinone radicals, the second‐order rate constant of which is typically 109 m−1 s−1, were successfully identified, helping clarify the previously hidden reaction pathways. Accordingly, our method may have wide applicability in exploring the dynamics of many electrochemical reactions, especially their ultrafast initial steps. [ABSTRACT FROM AUTHOR]

The development of highly sensitive and selective uranyl ion (UO22+) probes has attracted significant attention owing to the threat to human health caused by high toxicity, radioactivity, and long half‐life. Herein, the development of aggregation‐induced emission (AIE) active polymer dots (Pdots) is described for an accurate UO22+ monitoring using a portable electrochemiluminescence (ECL) system. An AIE‐active polymer containing tetraphenylethene and boron ketoiminate moieties is prepared into Pdots and modified with ssDNA to capture UO22+, which can amplify the ECL signal of the Pdots through a resonance energy transfer mechanism. This probe provides an ultralow detection limit of 10.6 pm/2.5 ppt, which is at least two orders of magnitude lower than the known UO22+ luminescent probes. Only UO22+ can provide an obvious ECL enhancement among the various metal ions, indicating the excellent selectivity of this probe. Furthermore, a portable ECL analyzer is designed to realize UO22+ measurements in the wild. The anodic ECL mechanism of UO22+ is discovered and ECL technology is first applied in monitoring radioactive substances. This study provides a novel strategy for the development of accurate UO22+ probes and a practical UO22+ monitoring method, indicating its potential application in the environmental and energy fields. [ABSTRACT FROM AUTHOR]

The emergence of the rising alliance between aggregation‐induced emission (AIE) and electrochemiluminescence (ECL) is defined as aggregation‐induced electrochemiluminescence (AIECL). The booming science of AIE has proved to be not only distinguished in luminescent materials but could also inject new possibility into ECL analysis. Especially in the aqueous phase and solid state for hydrophobic materials, AIE helps ECL circumvent the dilemma between substantial emission intensity and biocompatible media. The wide range of analytes makes ECL an overwhelmingly interesting analytical technique. Therefore, AIECL has gained potential in clinical diagnostics, environmental assays, and biomarker detections. This review will focus on introduction of the novel concept of AIECL, current applied luminophores, and related applications developed in recent years. [ABSTRACT FROM AUTHOR]

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Abstract: Ionic current rectification (ICR) based nanopipettes allow accurate monitoring of cellular behavior in single living cells. Herein, we proposed a 30 nm nanopipette functionalized with G‐quadruplex DNAzyme as an efficient biomimetic recognizer for ROS generation at subcellular level via the changes of current–voltage relationship. Taking advantages of the ultra‐small tip, the nanopipette could penetrate into a single living cell repeatedly or keep measuring for a long time without compromising the cellular functions. Coupled with precision nanopositioning system, generation of ROS in mitochondria in response to cell inflammation was determined with high spatial resolution. Meanwhile, the changes of aerobic metabolism in different cell lines under drug‐induced oxidative stress were monitored continuously. We believe that the ICR‐nanopipette could be developed as a powerful approach for the study of cellular activities via electrochemical imaging in living cells. [ABSTRACT FROM AUTHOR]

Abstract: Noble metal nanoparticles are promising catalysts in electrochemical reactions, while understanding the relationship between the structure and reactivity of the particles is important to achieve higher efficiency of electrocatalysis, and promote the development of single‐molecule electrochemistry. Electrogenerated chemiluminescence (ECL) was employed to image the catalytic oxidation of luminophore at single Au, Pt, and Au‐Pt Janus nanoparticles. Compared to the monometal nanoparticles, the Janus particle structure exhibited enhanced ECL intensity and stability, indicating better catalytic efficiency. On the basis of the experimental results and digital simulation, it was concluded that a concentration difference arose at the asymmetric bimetallic interface according to different heterogeneous electron‐transfer rate constants at Au and Pt. The fluid slip around the Janus particle enhanced local redox reactions and protected the particle surface from passivation. [ABSTRACT FROM AUTHOR]

Judiciously integrated nanostructured materials/cellular interfaces could be applied for various applications including physiological monitoring. Physiological H2S is the third most important endogenously generated gasotransmitter and is believed to be related with many diseases. This work reports the novel photoelectrochemical (PEC) probing of cellular interfaces and the evaluation of cellular H2S production based on in situ-generated CdS-enhanced TiO2 nanotube (NT) heterostructures. We chose the TiO2 NT array in particular, owing to its structure of regular oriented vertical NTs (which permits fast directional charge transport) and its substantial inner cavity (which guarantees the highly efficient guest loading and molecule capture). HepG2 cells directly grown on and interfacing with the TiO2 NTs are then used for the activation of the TiO2 NTs through the CdS generated in situ on the TiO2 NTs. Owing to the aforementioned unique properties of TiO2 NTs, even small amounts of in situ-generated CdS could be detected and result in apparent electrical signals. To the best of our knowledge, such TiO2 NT-based in situ PEC probing of cellular interfaces and evaluation of H2S cellular production have not previously been reported. [ABSTRACT FROM AUTHOR]

A crack-free sub-nanometer composite structure for the study of ion transfer was constructed by in situ growth of ZIF-90 [Zn(ICA)2, ICA=Imidazole-2-carboxaldehyde] on the tip of a glass nanopipette. The potential-driven ion transfer through the sub-nanometer channels in ZIF-90 is strongly influenced by the pH of the solution. A rectification ratio over 500 is observed in 1 m KCl solution under alkaline conditions (pH 11.58), which is the highest value reported under such a high salt concentration. Fluorescence experiments show the super-high rectification ratio under alkaline conditions results from the strong electrostatic interaction between ions and the sub-nanometer channels of ZIF-90. In addition to providing a general pathway for further study of mass-transfer process through sub-nanometer channels, the approach enable all kinds of metal-organic frameworks (MOFs) to be used as ionic permselectivity materials in nanopore-based analysis. [ABSTRACT FROM AUTHOR]

An advanced biosensor based on a closed bipolar electrode (BPE)-electrochemiluminescence (ECL) strategy is proposed for cancer cell adhesion, specific recognition, and detection with dual biomarkers. The system consists of a two-channel polydimethylsiloxane (PDMS) chip (sensing channel and reporting channel) connected through a U-shaped indium tin oxide BPE at a glass surface. A sandwich-type cancer cell detection model is developed at the cathode of the BPE with two recognition molecules, folic acid (FA) and an aptamer. On the basis of the high affinity between FA and the folate receptor that is overexpressed at a cancer cell membrane as well as the excellent conductivity of graphene-Au conjugates, this strategy could achieve the sensitive detection of HL-60 cells, with a limit as low as 18 cells in 30 μL of cell suspension. Control experiments confirm that the sandwich assay specifically captures cancer cells and recognizes target cells. [ABSTRACT FROM AUTHOR]

Photoelectrochemical (PEC) biosensing with semiconductor quantum dots (QDs) has received great attention because it integrates the advantages of both photo-excitation and electrochemical detection. During the photon-to-electricity conversion in PEC processes, electron-hole (charge) separation competes with electron-hole recombination, and the net effect essentially determines the performance of PEC biosensors. Herein, we propose a new approach for slowing down electron-hole recombination to increase charge separation efficiency for PEC biosensor development. Through doping with Mn2+, a pair of d bands (4T1 and 6A1) is inserted between the conduction and valence bands of CdS QDs, which alters the electron-hole separation and recombination dynamics, allowing the generation of long-lived charge carriers with ms-scale lifetime that decay about 104-105-fold more slowly than in the case of undoped QDs. Photocurrent tests indicated that Mn2+ doping resulted in an approximately 80 % increase in photocurrent generation compared with undoped CdS QDs. For application, the Mn-doped CdS QDs were coated on the surface of a glassy carbon electrode and functionalized with a cell surface carbohydrate-specific ligand (3-aminophenylboronic acid). In this way, a sensitive cytosensor for K562 leukemia cells was constructed. Moreover, the sugar-specific binding property of 3-aminophenylboronic acid allowed the electrode to serve as a switch for the capture and release of cells. This has been further explored with a view to developing a reusable PEC cytosensing platform. [ABSTRACT FROM AUTHOR]

In this work, a simple and effective approach to obtain stable, nontoxic and strong electrochemiluminescence (ECL) interfaces is provided by coating TiO2 nanoparticles (NPs) modified glassy carbon electrode (GCE) surfaces with Nafion. Unlike a decrease of the current resulting from the blocked diffusion usually displayed in electrochemical processes by Nafion coating, a Nafion/TiO2 NPs modified electrode not only shows a highly stable ECL, but also shows an 8-fold increase of ECL intensity and a reduction of the overpotential of ca. 300 mV in the presence of K2S2O8 as co-reactant, compared with those of bare TiO2 NPs modified electrodes. The roles of Nafion coating on TiO2 NPs in the ECL process are proposed to be twofold: to provide refuge for the free radicals and to enhance the electron-hole recombination. Benefiting from its excellent ECL performance, the cationic exchange function of Nafion and the susceptible to being oxidized performance of dopamine (DA) by holes, the Nafion/TiO2 composite electrode could be used to sensitively and selectively detect DA with a detection limit of 1.0×10−11 M and a linear range of 1.0×10−11-6.0×10−7 M. The coexisting anionic species such as excess ascorbic acid show little interference on DA detection. [ABSTRACT FROM AUTHOR]

Co2+ doped CdSe nanocrystals (CdSe:Co NCs) have been synthesized via a co-precipitation method in homogeneous solutions. The anodic electrochemiluminescence (ECL) of CdSe:Co NCs with tripropylamine (TPrA) as co-reactant was studied in aqueous solution for the first time. Co2+ doped IIVI NCs systems exhibit strong coupling due to Co d-orbital mixing with the valence band and conduction band of the IIVI host, which causes a ca. 3-fold enhancement in ECL intensity compared with the undoped CdSe NCs. Benefiting from the strong anodic ECL emission of the doped NCs, we developed an alkaline phosphatase (ALP)-responsive ECL system to detect the enzymatic processes successfully. An inhibition type anodic ECL strategy has been used to sensitively detect ALP ranging from 0.5 nM to 10 nM, with a detection limit of 0.1 nM. [ABSTRACT FROM AUTHOR]